The organization of the brain-stem respiratory and vasomotor centers, and their interrelations between the two systems, will be studied with the goal of explaining how the motor outputs (respiratory and sympathetic nerve discharge) arise from interactions in populations of brain-stem neurons. The principle of analysis of functional connections will be to study the temporal relations between brain-stem activity (both populatin and unit) and the appropriate motor output, as well as the temporal relations between different brain-stem activities. These relations will be observed both during spontaneous activity and during evoked activity changes due to experimental forcing inputs (with particular emphasis on brain-stem electrical stimulation). The data will be analyzed by the computer methods of averaging summation, autocorrelation, and crosscorrelation. The project will provide information on the neural basis of normal respiratory and vasomotor activity and therefore also on changes in various physiological and pathological conditions (e.g., dyspnea, hypertension, and shock). Further, the results should cast light on the general theory of interactions within neuronal networks, including the general problem of the origin of spontaneous activity. Bibliographic references: Gootman, P.M., Cohen, M.I., Piercey, M.F., & Wolotsky, P. A search for medullary neurons with activity patterns similar to those in sympathetic nerves. Brain Res., 1975, 87:395-406; Cohen, M.I. Phrenic and recurrent laryngeal discharge patterns and the Hering-Breuer reflex. Am. J. Physiol., 1975, 228: 1489-1496.